Originally Posted by Seejay

I have never seen a study that says a person can do the same work when calories from diet are either 3000 or 500.

Originally Posted by grinch031

I also question all the people who eat very little on Atkins but stall. Is there any evidence that the person is truly not burning fat even though their calorie intake is likely much lower than they need?

Originally Posted by grinch031

I don't dispute that. Its really how much of a change it would have on the metabolism that I dispute.

I also question all the people who eat very little on Atkins but stall. Is there any evidence that the person is truly not burning fat even though their calorie intake is likely much lower than they need?

Originally Posted by shannone10

Honestly, I think you are just trying to start something here.

None of the mainstream low carb plans recommend such a thing as 500 calories a day. That is a myth. There is variation between these diet plans. But they all tend to promote the idea that cutting back on starchy foods in favor of proteins, veggies and fats is healthier than a diet based on things like bread, pasta and potatoes. Based on the premise that the evolution of our metabolic systems has not kept up with the relatively recent availability and predominance of of these starches in the Standard American Diet, leading to things like obesity and type 2 diabetes.

Your question seems to be meanderingly directed at a hypothetical "stall" in a situation that even the Atkins diet would not ever advocate. That's why I think you are blowing smoke.

Originally Posted by LaZigeuner

I mean---what if (1) calories in affects calories out, and (2) calories out affects calories in: eating more calories causes expenditure of more calories; and expending more calories causes eating of more calories.

What besides a complex system can possibly account for it? One answer is that the "system" is not exactly the same for the 3000 cal scenario and the 500 cal scenario.

It depends on what XYZ are. If to the body, X > Y > Z in importance, then the body that requires 3000 cals to do X+Y+Z but now only gets 500 cals, may only do X. But if the body continues to do XYZ on 500 cals, it may make several other changes, such as eliminating ABCDEFGH and cutting XYZ down to a minimum. These changes create a totally different system than the original, in other words, a different physiological environment on the latter (500 cals) than the former (3000 cals).

If Y or Z is exercise (voluntary large muscle movement), consider how efficient our large muscles are in terms of energy expenditure.



Cites please. And be skeptical of the skeptics (it's fun).



You didn't read the whole study. They differentiated between lost body water, lost body weight, and lost LBM, iirc. (All together these allow deductions about lost body fat.)

I hope you enjoy it. And be skeptical of what you read (because it's fun).

Originally Posted by Rosebud

I guess I don't understand what it is you don't understand about starvation mode. It seems that you don't believe it happens. Because it really does. It happens to me consistently if I keep my calories too low, as it has happened to many, many other people. And every time I/we add more calories, kaboom, weight loss recommences.

I can't tell you exactly why, but don't doubt the truth of it, because it is a very real entity.

Originally Posted by Rosebud

I guess I don't understand what it is you don't understand about starvation mode. It seems that you don't believe it happens. Because it really does. It happens to me consistently if I keep my calories too low, as it has happened to many, many other people. And every time I/we add more calories, kaboom, weight loss recommences.

I can't tell you exactly why, but don't doubt the truth of it, because it is a very real entity.

Originally Posted by grinch

And that myth being that your metabolism slows down drastically when taking in too few calories.

Originally Posted by Judynyc

Its not a myth at all. Its in our DNA for survival during famine. If a person eats 500 calories a day for an extended period of time, their metabolism will slow as a method of survival because the body will react as if its being starved to death. The body adjusts to survive.
Not much more to explain or understand about it...its just the way we've evolved as a race.

Originally Posted by shannone10

On this note, I feel like I need to cut the OP some slack.

An expert has just chimed in with the scientific explanation that "...it happens, it really does......". And this person has posted here almost 20 thousand times????

Wow.......

Originally Posted by grinch031

'for an extended period of time' is where the myth turns into truth. If its for an extended period of time then you are going to burn tons of fat before you hit the point where your body's metabolism has to shut down. But once it shuts down you can't really do anything physically, which explains how you can function on so few calories.

That is not the same scenario as the advice given by dieticians that dropping below 1200 calories will halt your metabolism almost immediately.

But regardless I'm satisfied with some of the info and links I got on the subject here.

Originally Posted by leemack

If your metabolism halted completely you'd be dead!

As Judy says, your body doesn't understand that you're dieting and trying to lose weight. It just sees 'famine' and slows the metabolism to try and compensate. Its a survival mechanism, as your body doesn.t know when food availability is going to increase, and wants to keep itself alive as long as possible.

Most people will lose on a 500 cal a day diet because the metabolism has difficulty slowing that much - it has to keep processes going, but there would be a lot of muscle loss. What generally happens is a person eats a very low calorie diet, can't keep it up indefinately, returns to eating what is still low calorie - say 1200 cal a day and find their metabolism has slowed to the point that they put on weight at this level of caloric intake.

There was someone who started a thread last week about having their BMR measured and it had dropped to 800 calories a day - this was someone who had been eating excessively low calories for an extended period - and they excercise a lot.

Lee

Originally Posted by grinch031

I'm perfectly fine with the idea that your calorie intake puts your body into a state to conserve energy. But my main point is that if the BMR drops that much, then the physical ability to exercise must also drop to account for the loss of energy.

So if I think it would seem more believable if a dietician were to say instead of following the 1200 calorie rule, they should not restrict calories such that it reduces their ability to be physically active and exercise. Because that fatigue would be an indicator that their metabolism has slowed down significantly.

Originally Posted by leemack

Why do you think the ability to do physical activity is the the thing most affected - in times of famine activity is essential to find food, so limiting the ability to be active for the time it takes to search for food would be counterproductive. But if you tested your brainpower before and during 'starvation mode' you'd see a marked difference - the brain uses lots of energy.

With a low carb diet, eating to hunger is the best way to gauge calorie requirement - not artificially lowering calories. Your body will tell you how much food it needs if you feed it right, and learn to listen to it. The only caveat to that is those trying to lose those last vanity pounds.

Lee